Integration of absorption based heating bake methods into a photolithography track system

ABSTRACT

A method of patterning a layered substrate is provided that includes forming a layer of a block copolymer on a substrate; and annealing the layer of the block copolymer to affect microphase segregation such that self-assembled domains are formed by application of an absorption based heating method. Exemplary absorption based heating methods include electromagnetic radiation sources such as broadband flash lamps, light emitting diodes, lasers, or DUV flash lamps. The method may also include a metrology review and an application of the absorption based heating to at least a portion of the layered substrate to refine or modify the microphase segregation.

CROSS-REFERENCE TO RELATED APPLICATIONS

Pursuant to 37 C.F.R. §1.78(a)(4), this application claims the benefitof and priority to prior filed co-pending Provisional Application Ser.No. 61/782,133 filed on Mar. 14, 2013, the disclosure of which isincorporated herein by reference in its entirety.

FIELD OF THE INVENTION

This disclosure is related to methods for integrating absorption basedheating bake methods in directed self-assembly applications.

BACKGROUND OF THE INVENTION

Directed self-assembly (“DSA”) processes use block copolymers to formlithographic structures. There are a host of different integrations forDSA (e.g., chemo-epitaxy, grapho-epitaxy, hole shrink, etc.), but in allcases the technique depends on the rearrangement of the block copolymerfrom a random, unordered state to a structured, ordered state that isuseful for subsequent lithography. The morphology of the ordered stateis variable and depends on a number of factors, including the nature ofthe block polymers, relative molecular weight ratio between the blockpolymers, and the annealing conditions. Common morphologies includeline-space and cylindrical, although other structures may also be used.For example, other ordered morphologies include spherical, lamellar,bicontinuous gyroid, or miktoarm star microdomains.

Annealing of the block copolymer layer has traditionally been achievedby various methods known in the art, including, but not limited to:thermal annealing (either in a vacuum or in an inert atmospherecontaining nitrogen or argon), solvent vapor-assisted annealing (eitherat or above room temperature), or supercritical fluid-assistedannealing. As a specific example, thermal annealing of the blockcopolymer can be conducted at an elevated temperature that is above theglass transition temperature (Tg), but below the degradation temperature(Td) of the block copolymer. However, to generate well-registeredpatterns, thermal annealing, solvent vapor-assisted annealing, andsupercritical fluid-assisted annealing each have their own inherentlimitations.

For example, thermal annealing of some block copolymers (e.g.,polystyrene-b-polymethacrylate) may be accomplished in relatively shortprocessing times. But to achieve reductions in critical dimensions andline edge roughness, the use of block copolymers with largerFlory-Huggins interaction parameter (χ) may be required. But the higherχ block copolymers generally have slower self-assembly kinetics, andself-assembled pattern generation may take a few to tens of hours, thusdetrimentally affecting throughput. Solvent vapor-assisted annealing canimprove the kinetics of the self-assembly of higher χ block copolymersbut involves the introduction of another component to the system withits own hardware and process constraints.

Accordingly, there is a need for new apparatus and methods for annealingblock copolymers in DSA applications.

SUMMARY OF THE INVENTION

The present invention overcomes the foregoing problems and othershortcomings, drawbacks, and challenges of conventional annealingprocess for directed self-assembly applications. While the inventionwill be described in connection with certain embodiments, it will beunderstood that the invention is not limited to these embodiments. Tothe contrary, this invention includes all alternatives, modifications,and equivalents as may be included within the scope of the presentinvention.

According to an embodiment of the present invention, a method forpatterning a layered substrate is provided. The method comprises a)forming a layer of a block copolymer; and b) annealing the layer of theblock copolymer to affect microphase segregation such thatself-assembled domains are formed, wherein the annealing is performed byapplication of an absorption based heating method provided by exposureto electromagnetic radiation to provide an annealing temperature in arange of 250° C. to 500° C.

According to another embodiment, a method of patterning a layeredsubstrate is provided that comprises a) forming a layer of a blockcopolymer; b) performing a first annealing treatment of the layer of theblock copolymer to affect microphase segregation such thatself-assembled domains are formed; and c) exposing at least a portion ofthe layer of the block copolymer to electromagnetic radiation to heatthe exposed portion of the layer of the block copolymer to an annealingtemperature in a range of 250° C. to 500° C.

The above and other objects and advantages of the present inventionshall be made apparent from the accompanying drawings and thedescriptions thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate embodiments of the presentinvention and, together with a general description of the inventiongiven above, and the detailed description of the embodiments givenbelow, serve to explain the principles of the present invention.

FIG. 1 is a flow chart illustrating a method of incorporating anabsorption based heating method for annealing a layered substratecomprising a layer of a block copolymer, in accordance with anembodiment of the present invention;

FIG. 2 is a flow chart illustrating another method of incorporating anabsorption based heating method for annealing a layered substratecomprising a layer of a block copolymer, in accordance with anembodiment of the present invention; and

FIG. 3 is a flow chart illustrating another method of incorporating anabsorption based heating method for annealing a layered substratecomprising a layer of a block copolymer, in accordance with anembodiment of the present invention.

DETAILED DESCRIPTION

Apparatus and methods for incorporating an absorption based heatingannealing technique within direct self-assembly (“DSA”) applications aredisclosed in various embodiments. However, one skilled in the relevantart will recognize that the various embodiments may be practiced withoutone or more of the specific details or with other replacement and/oradditional methods, materials, or components. In other instances,well-known structures, materials, or operations are not shown ordescribed in detail to avoid obscuring aspects of various embodiments ofthe present invention.

Similarly, for purposes of explanation, specific numbers, materials, andconfigurations are set forth in order to provide a thoroughunderstanding. Nevertheless, the embodiments of the present inventionmay be practiced without specific details. Furthermore, it is understoodthat the illustrative representations are not necessarily drawn toscale.

Reference throughout this specification to “one embodiment” or “anembodiment” or variation thereof means that a particular feature,structure, material, or characteristic described in connection with theembodiment is included in at least one embodiment of the invention, butdoes not denote that they are present in every embodiment. Thus, theappearances of the phrases such as “in one embodiment” or “in anembodiment” in various places throughout this specification are notnecessarily referring to the same embodiment of the invention.Furthermore, the particular features, structures, materials, orcharacteristics may be combined in any suitable manner in one or moreembodiments. Various additional layers and/or structures may be includedand/or described features may be omitted in other embodiments.

Additionally, it is to be understood that “a” or “an” may mean “one ormore” unless explicitly stated otherwise.

Various operations will be described as multiple discrete operations inturn, in a manner that is most helpful in understanding the invention.However, the order of description should not be construed as to implythat these operations are necessarily order dependent. In particular,these operations need not be performed in the order of presentation.Operations described may be performed in a different order than thedescribed embodiment. Various additional operations may be performedand/or described operations may be omitted in additional embodiments.

In accordance with an embodiment of the present invention and inreference to the flow chart of FIG. 1, a method 100 for patterning alayered substrate is provided. The method 100 comprises a) forming alayer of a block copolymer (110) on a substrate; and b) annealing thelayer of the block copolymer by applying an absorption based heatingmethod (120). Optionally, a metrology review of the annealed layeredsubstrate may be performed to identify or quantify areas of non-directedself-assembly, which upon exceeding a predetermined threshold value caninitiate one or more additional annealing steps to refine or modify themicrophase segregation of the block copolymers. In accordance withembodiments of the present invention, the one or more additionalannealing steps may include an absorption based annealing step or atraditional annealing step, as further described below.

As used herein, the term “polymer block” means and includes a groupingof multiple monomer units of a single type (i.e., a homopolymer block)or multiple types (i.e., a copolymer block) of constitutional units intoa continuous polymer chain of some length that forms part of a largerpolymer of an even greater length and exhibits a χN value, with otherpolymer blocks of unlike monomer types, that is sufficient for phaseseparation to occur. χ is the Flory-Huggins interaction parameter, whichis temperature dependent, and N is the total degree of polymerizationfor the block copolymer. According to embodiments of the presentinvention, the χN value of one polymer block with at least one otherpolymer block in the larger polymer may be equal to or greater thanabout 10.5, at the annealing temperature.

As used herein, the term “block copolymer” means and includes a polymercomposed of chains where each chain contains two or more polymer blocksas defined above and at least two of the blocks are of sufficientsegregation strength (e.g. χN>10.5) for those blocks to phase separate.A wide variety of block polymers are contemplated herein includingdiblock copolymers (i.e., polymers including two polymer blocks (AB)),triblock copolymers (i.e., polymers including three polymer blocks (ABAor ABC)), multiblock copolymers (i.e., polymers including more thanthree polymer blocks (ABCD, star copolymers, miktoarm polymers, etc.)),and combinations thereof.

According to an embodiment of the present invention, the directedself-assembly block copolymer is a block copolymer comprising a firstpolymer block and a second polymer block, where the first polymer blockinherently has an etch selectivity greater than 2 over the second blockpolymer under a first set of etch conditions. According to oneembodiment, the first polymer block comprises a first organic polymer,and the second polymer block comprises a second organic polymer. Inanother embodiment, the first polymer block is an organic polymer andthe second polymer block is an organometallic-containing polymer. Asused herein, the organometallic-containing polymer includes polymerscomprising inorganic materials. For example, inorganic materialsinclude, but are not limited to, metalloids such as silicon, and/ortransition metals such as iron.

It will be appreciated that the total size of each block copolymer andthe ratio of the constituent blocks and monomers may be chosen tofacilitate self-organization and to form organized block domains havingdesired dimensions and periodicity. For example, it will be appreciatedthat a block copolymer has an intrinsic polymer length scale, theaverage end-to-end length of the copolymer in film, including anycoiling or kinking, which governs the size of the block domains. Acopolymer solution having longer copolymers may be used to form largerdomains and a copolymer solution having shorter copolymers may be usedto form smaller domains.

Moreover, the types of self-assembled microdomains formed by the blockcopolymer are readily determined by the volume fraction of the firstblock component to the second block components.

According to one embodiment, when the volume ratio of the first blockcomponent to the second block component is greater than about 80:20, orless than about 20:80, the block copolymer will form an ordered array ofspheres composed of the second polymeric block component in a matrixcomposed of the first polymeric block component. Conversely, when thevolume ratio of the first block component to the second block componentis less than about 20:80, the block copolymer will form an ordered arrayof spheres composed of the first polymeric block component in a matrixcomposed of the second polymeric block component.

When the volume ratio of the first block component to the second blockcomponent is less than about 80:20 but greater than about 65:35, theblock copolymer will form an ordered array of cylinders composed of thesecond polymeric block component in a matrix composed of the firstpolymeric block component. Conversely, when the volume ratio of thefirst block component to the second block component is less than about35:65 but greater than about 20:80, the block copolymer will form anordered array of cylinders composed of the first polymeric blockcomponent in a matrix composed of the second polymeric block component.

When the volume ratio of the first block component to the second blockcomponent is less than about 65:35 but is greater than about 35:65, theblock copolymer will form alternating lamellae composed of the first andsecond polymeric block components.

Therefore, the volume ratio of the first block component to the secondblock component can be readily adjusted in the block copolymer in orderto form desired self-assembled periodic patterns. According toembodiments of the present invention, the volume ratio of the firstblock component to the second block component is less than about 80:20but greater than about 65:35 to yield an ordered array of cylinderscomposed of the second polymeric block component in a matrix composed ofthe first polymeric block component.

Block copolymers may be comprised of exemplary organic polymer blocksthat include, but are not limited to,poly(9,9-bis(6′-N,N,N-trimethylammonium)-hexyl)-fluorene phenylene)(PFP), poly(4-vinylpyridine) (4PVP), hydroxypropyl methylcellulose(HPMC), polyethylene glycol (PEG), poly(ethyleneoxide)-co-poly(propylene oxide) di- or multiblock copolymers, poly(vinylalcohol) (PVA), poly(ethylene-co-vinyl alcohol) (PEVA), poly(acrylicacid) (PAA), polylactic acid (PLA), poly(ethyloxazoline), apoly(alkylacrylate), polyacrylamide, a poly(N-alkylacrylamide), apoly(N,N-dialkylacrylamide), poly(propylene glycol) (PPG),poly(propylene oxide) (PPO), partially or fully hydrolyzed poly(vinylalcohol), dextran, polystyrene (PS), polyethylene (PE), polypropylene(PP), polyisoprene (PI), polychloroprene (CR), a polyvinyl ether (PVE),poly(vinyl acetate) (PV_(Ac)), poly(vinyl chloride) (PVC), apolyurethane (PU), a polyacrylate, an oligosaccharide, or apolysaccharide.

Block copolymers may be comprised of exemplary organometallic-containingpolymer blocks that include, but are not limited to, silicon-containingpolymers such as polydimethylsiloxane (PDMS), polyhedral oligomericsilsesquioxane (POSS), or poly(trimethylsilylstyrene (PTMSS), orsilicon- and iron-containing polymers such aspoly(ferrocenyldimethylsilane) (PFS).

Exemplary block copolymers include, but are not limited to, diblockcopolymers such as polystyrene-b-polydimethylsiloxane (PS-PDMS),poly(2-vinylpyridine)-b-polydimethylsiloxane (P2VP-PDMS),polystyrene-b-poly(ferrocenyldimethylsilane) (PS-PFS), orpolystyrene-b-poly-DL-lactic acid (PS-PLA), or triblock copolymers suchas polystyrene-b-poly(ferrocenyldimethylsilane)-b-poly(2-vinylpyridine)(PS-PFS-P2VP),polyisoprene-b-polystyrene-b-poly(ferrocenyldimethylsilane) (PI-PS-PFS),or polystyrene-b-poly(trimethylsilylstyrene)-b-polystyrene(PS-PTMSS-PS). In one embodiment, a PS-PTMSS-PS block copolymercomprises a poly(trimethylsilylstyrene) polymer block that is formed oftwo chains of PTMSS connected by a linker comprising four styrene units.Modifications of the block copolymers is also envisaged, such as thatdisclosed in U.S. Patent Application Publication No. 2012/0046415, theentire disclosure of which is incorporated by reference herein.

Embodiments of the invention may also allow for the formation offeatures smaller than those that may be formed by block polymers aloneor photolithography alone. In embodiments of the invention, aself-assembly material formed of different chemical species is allowedto organize to form domains composed of like chemical species. Portionsof those domains are selectively removed to form temporary placeholdersand/or mask features. A pitch multiplication process may then beperformed using the temporary placeholders and/or mask features formedfrom the self-assembly material. Features with a pitch smaller than apitch of the temporary placeholders may be derived from the temporaryplaceholders.

Moreover, because the block copolymer material is also used as a maskfor patterning underlying layers, the copolymer material is selected notonly on its self-assembly behavior, but also based on its etchselectivity between the polymer blocks. Accordingly, the self-assemblybehavior of the block copolymers allows the reliable formation of verysmall features, thereby facilitating the formation of a mask with a verysmall feature size. For example, features having a critical dimension ofabout 1 nm to about 100 nm, about 3 nm to about 50 nm or about 5 nm toabout 30 nm may be formed.

As used herein, the term “substrate” means and includes a base materialor construction upon which materials are formed. It will be appreciatedthat the substrate may include a single material, a plurality of layersof different materials, a layer or layers having regions of differentmaterials or different structures in them, etc. These materials mayinclude semiconductors, insulators, conductors, or combinations thereof.For example, the substrate may be a semiconductor substrate, a basesemiconductor layer on a supporting structure, a metal electrode or asemiconductor substrate having one or more layers, structures or regionsformed thereon. The substrate may be a conventional silicon substrate orother bulk substrate comprising a layer of semiconductive material. Asused herein, the term “bulk substrate” means and includes not onlysilicon wafers, but also silicon-on-insulator (“SOI”) substrates, suchas silicon-on-sapphire (“SOS”) substrates and silicon-on-glass (“SOG”)substrates, epitaxial layers of silicon on a base semiconductorfoundation, and other semiconductor or optoelectronic materials, such assilicon-germanium, germanium, gallium arsenide, gallium nitride, andindium phosphide. The substrate may be doped or undoped.

The terms “microphase segregation” and “microphase separation,” as usedherein mean and include the properties by which homogeneous blocks of ablock copolymer aggregate mutually, and heterogeneous blocks separateinto distinct domains. In the bulk, block copolymers can self assembleinto ordered morphologies, having spherical, cylindrical, lamellar, orbicontinuous gyroid microdomains, where the molecular weight of theblock copolymer dictates the sizes of the microdomains formed. Thedomain size or pitch period (L₀) of the self-assembled block copolymermorphology may be used as a basis for designing critical dimensions ofthe patterned structure. Similarly, the structure period (L_(S)), whichis the dimension of the feature remaining after selectively etching awayone of the polymer blocks of the block copolymer, may be used as a basisfor designing critical dimensions of the patterned structure.

The lengths of each of the polymer blocks making up the block copolymermay be an intrinsic limit to the sizes of domains formed by the polymerblocks of those block copolymers. For example, each of the polymerblocks may be chosen with a length that facilitates self-assembly into adesired pattern of domains, and shorter and/or longer copolymers may notself-assemble as desired.

The term “annealing” or “anneal” as used herein means and includestreatment of the block copolymer so as to enable sufficient microphasesegregation between the two or more different polymeric block componentsof the block copolymer to form an ordered pattern defined by repeatingstructural units formed from the polymer blocks.

In accordance with an embodiment, annealing of the block copolymer isperformed by only applying an absorption based heating method. Inaccordance with another embodiment, annealing the layer of the blockcopolymer may be performed by any traditional or absorption basedheating method to affect microphase segregation to form ordered domains,but then is subsequently followed by an absorption based heating methodto refine or modify the microphase segregation. In accordance withanother embodiment, annealing the layer of the block copolymer layer maybe first performed by an absorption based heating method, but is thensubsequently followed by a traditional annealing method. “Traditional”annealing methods include, but are not limited to, a single wafer bakeplate under ambient or low O₂ (e.g., 50 ppm) conditions; a batch waferbake furnace under ambient or low O₂ conditions; a single wafer solventbake plate under a variety of solvent conditions; or a batch wafer bakefurnace under a variety of solvent bake conditions.

As used herein, “absorption based heating” or “optical based heating” isbased on the absorbance of radiation or electromagnetic energy that israpidly converted to thermal energy. Absorption based heating allows forincreased thermal ramp rates and thermal quenches, relative totraditional ovens, furnaces, or heated wafer chucks. These higher ramprates/thermal quenches allow for a much wider operating range for timeand temperature permutations, often allowing for significantly highertemperatures for a given layered material under less than idealenvironment. Exemplary absorption based annealing temperatures may be ina range from about 100° C. to about 1000° C., for example about 200° C.to about 1000° C., about 500° C. to about 1000° C., about 800° C. toabout 1000° C., about 200° C. to about 800° C., or about 400° C. toabout 600° C. Other suitable absorption based annealing temperature maybe in a range from about 100° C. to about 500° C., for example fromabout 250° C. to about 500° C., about 100° C. to about 400° C., about200° C. to about 300° C., depending on the nature of the blockcopolymer.

As specific examples, optical absorption heating sources, such as LED,laser, ultraviolet, or broadband visible light may be used to heat thelayer of the block copolymer to an elevated temperature that is about50° C. or more above the intrinsic glass transition temperature (Tg),but below the order-disorder temperature (ODT) above which the blockcopolymer will no longer phase separate and also below the thermaldegradation temperature (Td) of the block copolymer, as described ingreater detail hereinafter.

As used herein, “intrinsic glass transition temperature” means the glasstransition temperature of the block copolymer without the influence ofwater or other solvents. As known in the art, the presence of solventslowers the temperature of the glassy transition of thesolvent-containing mixtures.

As used herein, “thermal degradation temperature” means a temperature atwhich the block copolymer will undergo oxidative degradation underambient oxygen levels. According to an embodiment of the presentinvention, the oxygen content in the surrounding atmospheres for theabsorption based annealing process and the thermal quench are at a levelequal to or less than about 50 ppm. The thermal degradation temperatureof a given block copolymer at the desired ambient oxygen level can beascertained by common methods, which includes but is not limited to,thermogravimetric analysis (TGA).

Optical based heating methods can also be used to replace traditionalprocessing methods at many potential process steps within aphotolithography process. Some traditional photolithography bake stepsthat it could replace are dehydration bake (to remove water on surfacefor better priming); bottom anti-reflective coating (BARC) bake(typically to crosslink the BARC to make insoluble to further resistprocess); photoresist bake (to remove majority of residual castingsolvent from resist film); post exposure bake (PEB) (to facilitatechemical amplified resists, CAR, acid diffusion and chemicalamplification kinetics); hard bake (to remove most residual solvent toimprove etch performance); or thermal freeze bake (forlithography-freeze, lithography etch (LFLE) double patterningprocesses).

According to embodiments of the present invention, the absorption basedheating methods may be applied using a uniform single exposure (e.g., aflood exposure) to electromagnetic radiation for a first duration oftime that is sufficient to rapidly heat the layer of the block copolymerabove the T_(g), which is followed by a sufficient time period ofnon-exposure to allow the layer of the block copolymer to cool below theT_(g). In another embodiment, as shown in FIG. 2, the absorption basedheating method (200) may include a) selecting a beam shape of theelectromagnetic radiation to distribute power across a predeterminedabsorption area (210); b) determining a number of scans for the selectedbeam shape to irradiate a desired area of the layer of the blockcopolymer with the electromagnetic radiation (220); and c) scanning thelayer of the block copolymer with the electromagnetic radiation to heatthe layer of the block copolymer to the annealing temperature range(230).

Absorption based heating methods integrated into DSA processes providethe ability to reach elevated temperatures for shorter periods of times,which can minimize oxidative or thermal degradation of the BCPmaterials. Absorption based heating methods can be performed by manypotential optical sources including, but not limited to, exposing thelayered substrate to an electromagnetic radiation source selected fromthe group consisting of a broadband flash lamp, a light emitting diode;a laser, and a deep ultraviolet (DUV) flash lamp. Exemplaryelectromagnetic radiation sources include broadband flash lamp sources(e.g., middle ultraviolet (MUV) radiation, visible light radiation, ornear infrared radiation (NIR), having a wavelength in a range from about300 nm to about 1100 nm); light emitting diodes (typically emittingradiation having a wavelength in a range from about 500 nm to about 1100nm); lasers, such as diode lasers (typically emitting radiation having awavelength in a range from about 500 nm to about 1100 nm, or from about800 nm to about 1000 nm), or CO₂ lasers (e.g., about 9.4 um or about10.6 um, etc.); or deep ultraviolet (DUV) flash lamp sources (typicallyemitting radiation having a wavelength in a range from about 150 nm toabout 200 nm).

The viability of any one electromagnetic source depends on the abilityof a media to absorb the light at the intended wavelength and uponabsorbing the light (photon) to convert absorbed light into thermalenergy (phonon). The absorbing media can be, depending on light sourcebeing considered, but is not limited to: the substrate itself, typicallySi; a modified substrate, to allow for absorption, such as heavily dopedSi; or the use of a uniform absorbance layer, as described in U.S.Patent Application Publication No. 2013/0288487, the entirety of whichis incorporated herein by reference in its entirety.

For some applications, the fluence, or power density, will be veryimportant to ensure the correct time/temperature regime is obtained.Depending on the electromagnetic radiation source and its construction,the power density may be in a range from about 1 W/mm² to about 100W/mm², or about 100 W/mm² to about 200 W/mm², or about 200 W/mm² toabout 300 W/mm², or about 300 W/mm² to about 400 W/mm², or about 400W/mm² to about 500 W/mm². Accordingly, the power density may be in arange from about 100 W/mm² to about 250 W/mm², or about 250 W/mm² toabout 500 W/mm².

In accordance with an embodiment of the present invention, theabsorption based heating provides an annealing temperature in a range of250° C. to 1000° C. In accordance with another embodiment, the annealingtemperature is in the range of 250° C. to 500° C., or 500° C. to 1000°C. While the BCP materials can withstand lower annealing temperatureswithout stringent control of oxygen level in the annealing environment,the microphase segregation at these lower temperatures to form ordereddomains can take hours, or even longer. For a given polymer, theannealing time can be substantially shortened by going to highertemperatures. But polymer degradation may also increase, so oxygenlevels need to be kept low to minimize polymer oxidation.Advantageously, polymer thermal degradation has shown nomemory/cumulative effect of previous thermal spike processes, so long asspike temperature is below some thermal degradation threshold associatedwith the spike dwell time. Thermal diffusion effects within anysubstrate begin to limit intermediate thermal dwell times that can beachieved (ultimately creating a bimodal thermal dwell timedistribution). Accordingly, absorption based heating thermal profileengineering can be used to give the thermodynamic processes more timeand thus provide a higher probability of achieving 100% of desireddirected self-assembly while still targeting a desire temperature todrive a given chi and thus a given morphology without leading to thermaldecomposition.

Depending on various factors, e.g., flood exposure, repeated scanexposure, or rastering exposure; the power density (fluence) of thesource; the absorbance efficiency of the layered substrate; and thedesired annealing temperature, the first duration of exposure may beperformed for about 0.1 milliseconds to about 10 seconds. For example,the first duration of exposure may be 0.4 milliseconds to about 10seconds, about 0.1 milliseconds to about 5 seconds, about 0.4milliseconds to about 5 seconds, about 1 second to about 10 seconds, orabout 1 second to about 5 seconds.

In accordance with an embodiment, the exposure to electromagneticradiation is performed at a power density in a range from 1 W/mm² to 100W/mm² for a duration of time to provide the annealing temperature in thedesired range. In another embodiment, the exposure to electromagneticradiation is performed at a power density in a range from 250 W/mm² to500 W/mm² for a duration of time to provide the annealing temperature.

The exposing duration may also be performed over a series of shortexposures to provide an incrementally facilitated annealing of the layerof the block copolymer. For example, rastering an electromagneticradiation beam over time ranges from about 10 milliseconds to about 50milliseconds with about 4 to about 200 passes, may provide a cumulativeabsorption based annealing treatment in a range from about 40milliseconds to about 10 seconds. In another example, rastering anelectromagnetic radiation beam over time ranges from about 10milliseconds to about 50 milliseconds with about 4 to about 20 passes,may provide a cumulative absorption based annealing treatment in a rangefrom about 40 milliseconds to about 1 second.

The cooling off period or “thermal quench” period between two or moreabsorption based heating treatments may be a passive process or assistedby utilizing an exterior cooling process. According to an embodiment ofthe present invention, thermally quenching the annealed layeredsubstrate may be performed in several manners. The thermal quenching maycomprise at least one of reducing a pressure of the second atmosphere,flowing convective gas around the layered substrate, contacting thelayered substrate with a wafer chuck in communication with a chillerunit, and/or contacting the layered substrate with cooling arms. Withrespect to the convective gas, the gas may comprise nitrogen, argon, orhelium, for example. The quenching may also comprise use of athermoelectric Peltier device. The quenching step may occur over aduration of time equal to or less than about 30 seconds to about 5minutes and/or at a rate greater than or equal to 50° C/minute. With theexample of PS-PDMS, the layered substrate may be quenched from atemperature of 340° C. to a temperature of 250° C. in 1 minute (i.e., ata rate of 90° C/minute). The quenching atmosphere may comprise a coolingchamber 14, specifically a cooling Front Opening Unified Pod (FOUP), awafer boat, or a wafer handler, for example.

Once the layered substrate has cooled to a desired quenchingtemperature, an optical metrology review of the layered substrate may beperformed to identify or quantify regions of non-uniformity or defects.The term “defect” or “defects” as used herein refers to any unwanteddiscontinuity in the translational, orientational, or chemicalcompositional order of a pattern. For example, a defect can be anunwanted notch, crack, bulge, bend or other physical discontinuity inthe surface feature of the pre-pattern, or a chemical compositionalchange in a surface area of a pre-pattern. In another example, when theblock copolymer pattern is defined by alternating lamellae, it may bedesirable that the lamellae in such a block copolymer pattern must bealigned along the same direction in order for the pattern to beconsidered defect-free. Defects in the lamellar patterns can havevarious forms, including dislocation (i.e., line defects arising fromperturbations in the translational order), disclination (i.e., linedefects arising from discontinuities in the orientational order), andthe like. Although it is generally desirable to minimize defects, norestriction is placed on the number of defects per unit area in thepre-pattern or block copolymer pattern formed thereon.

Exemplary metrology methods include, but are not limited to, techniquesthat compare color variation of the inspected layered substrate to abaseline sample of the typical color for a given product or photolayer.This baseline sample (hereinafter referred to as the “color baselist” or“baselist”) may be composed of data from a collection of a predeterminednumber of different layered substrates. Once the baselist is complete,multiple parameters can be calculated that may represent information orcharacteristics such as average color, flatness, and properties of thedie patterns. The information derived from the metrology review mayinclude a classification of the defect; and/or an identification of thedefect as a systematic defect or a nuisance defect. Another aspect ofthe metrology review relates to a computer-implemented method forbinning defects detected on layered substrate. The metrology review mayalso include comparing one or more characteristics of the defects to oneor more characteristics of DSA defects and one or more characteristicsof non-DSA defects. Automated macro defect inspectors (also known asADIs), such as those devices commercially available from Tokyo Electronor KLA-Tencor, may be utilized for defect evaluation.

Thus, in accordance with another embodiment of the invention, absorptionbased annealing processes may be used to correct DSA-related defects.Layered substrates that exceed a predetermined quantity of defects, orhaving regions of high density of defects, may be subjected to furtherabsorption based annealing treatments, either globally or locally with atargeted beam. Using a computer-implemented method for binning defectscan permit a localized or isolated exposure of the electromagneticradiation to the defect area to correct the DSA-related defect. In anembodiment, the absorption based heating tool receives input andcompletes one or more programmed, selective scans for a defectabsorption based heating anneal step.

Additionally, as shown in FIG. 3, in another embodiment, a method ofpatterning a layered substrate (300) is provided, the method comprisingforming a layer of a block copolymer (310); performing a first annealingtreatment of the layer of the block copolymer to affect microphasesegregation such that self-assembled domains are formed (320); andapplying an absorption based heating method to at least a portion of thelayer of the block copolymer to refine or modify microphase segregation(330). In accordance with this embodiment, the first annealing step maybe an absorbance based heating process, or another annealing method suchas any one or more traditional annealing methods. Exemplary traditionalannealing methods include thermal annealing (either in a vacuum, in alow oxygen atmosphere, or in an inert atmosphere, such as nitrogen orargon), solvent vapor-assisted annealing (either at or above roomtemperature), or supercritical fluid-assisted annealing As a specificexample, thermal annealing of the block copolymer may be conducted byexposing the block copolymer in an oven or furnace to an elevatedtemperature that is above the glass transition temperature (T_(g)), butbelow the thermal degradation temperature (T_(d)) of the blockcopolymer. The oxygen content of the annealing atmosphere may becontrolled to be less than about 100 ppm, less than about 50 ppm, lessthan about 40 ppm, less than about 30 ppm, or less than about 20 ppm,for example. Other conventional annealing methods not described hereinmay also be utilized.

In a further aspect of the two step anneal process of method 300, thesecond anneal step may also provide: 1) redundancy to ensure near 100%direct self-assembly as described above; 2) allow for shorter annealingprocess overall cycle time; 3) depending on absorption based heatingmethod, e.g. small laser beam exposure method, for the possibility ofmixed morphology within the same exposure die; or 4) tailoring a blockco-polymer etch selectivity improvement, if not targeting a goal ofcomplete elimination of breakthrough/clean-up etch step (prior totransfer).

Specific to the mixed morphology or order-to-order transition (OOT)two-step anneal aspect, the desired mixed morphology could be acquiredby two complementary approaches. In a first mixed morphology embodiment,a solvent-assisted anneal method is utilized in the first anneal step(320), wherein the block copolymer is assembled to a first morphology,which is dictated by ambient solvent concentration, partial pressure,and block co-polymer fraction. The second anneal step (330) is performedby exposing a subset of any exposure die's area to a controlledabsorption based heating method (e.g. a small rastering laser beamexposure) to induce a transformation from the first morphology to asecond morphology only in this subset area.

In a second OOT embodiment, the fact that the Flory-Huggins interactionparameter (χ) is temperature dependent (χ goes down as temperature goesup), along with the fact that many blocked copolymers go through severalphase transitions through χ at a given block co-polymer fraction areexploited. Accordingly, in this second OOT embodiment, the firstannealing treatment (320) is performed at a first anneal temperature toaffect microphase segregation to a first morphology. In one embodiment,a non-solvent based annealing step may be used. Subsequent to this firstannealing treatment, a second annealing treatment (330) is performedusing a controlled absorption based heating method on a subset of anyexposure die's area at a second anneal temperature, which issignificantly higher than the first anneal temperature. Thesignificantly higher second anneal temperature induces a transformationfrom the first morphology to a second morphology only in this subsetarea. In one embodiment, the difference between the first and the secondanneal temperatures is equal to or greater than about 50° C., equal toor greater than about 75° C., equal to or greater than about 100° C., orequal to or greater than about 150° C.

In either OOT embodiment, the second annealing treatment (330) maycomprise a rastering laser beam exposure, for example.

On the other hand, using the two-step heating process can be used toimprove etch selectivity between the polymer blocks of the blockcopolymer. In this embodiment, the first annealing treatment (320) isperformed at a first anneal temperature to affect microphase segregationto a first morphology. This first annealing treatment may be atraditional anneal process, an absorption base anneal process, or acombination thereof. After the block copolymer has achieved the desiredfirst morphological state, an absorption based heating method is appliedto a subset of any exposure die's area under appropriate conditions(e.g., temperature, fluence, duration, etc.) to improve polymer blocketch selectivity. In another aspect, the appropriate combination ofblock copolymer and absorption base heating method may completelyeliminate having to perform a breakthrough/clean-up etch step.

In a non-limiting example, a PS:PMMA block copolymer system can beannealed at a first anneal to induce self-assembly. Subjecting theannealed layered substrate to an absorption based heating methodcomprising a UV light source will induce cross-linking of the PS polymerblock. However, using the UV light source at a sufficient fluence andduration heats the exposed region to a temperature greater than theT_(d) of the PMMA polymer, which is less than the T_(d) of PS.Accordingly, the high temperature/short time nature of the UV absorptionbased heating method would facilitate PMMA decomposition but notsignificantly decompose the PS. In this regard, UV absorption basedheating method of this embodiment is analogous to an isopropanol (IPA)wet development step, which is commonly used for this purpose. However,even if complete removal of PMMA is not achieved, partially removing itwill result in less PMMA that would need to be removed in a subsequentetch step, and gives a larger/improved PS:PMMA etch selectivity processwindow. It should be appreciated that while a PS:PMMA case is described,this embodiment is not limited to this system only. For example, asilylated PMMA branch, which would provide a higher χ material, wouldalso undergo thermal decomposition of the silylated PMMA polymer blockunder similar conditions.

While the present invention has been illustrated by a description of oneor more embodiments thereof and while these embodiments have beendescribed in considerable detail, they are intended to restrict or inany way limit the scope of the appended claims to such detail.Additional advantages and modifications will readily appear to thoseskilled in the art. The invention in its broader aspects is thereforenot limited to the specific details, representative apparatus andmethod, and illustrative examples shown and described. Accordingly,departures may be made from such details without departing from thescope of the general inventive concept.

What is claimed is:
 1. A method of patterning a layered substrate,comprising: a) forming a layer of a block copolymer; and b) annealingthe layer of the block copolymer to affect microphase segregation suchthat self-assembled domains are formed, wherein the annealing isperformed by application of an absorption based heating method providedby exposure to electromagnetic radiation to provide an annealingtemperature in a range of 250° C. to 500° C.
 2. The method of claim 1,wherein the exposure to electromagnetic radiation is performed at apower density in a range from 1 W/mm² to 100 W/mm² for a duration oftime in a range from 1 second to 10 seconds.
 3. The method of claim 1,wherein the absorption based heating method is provided by exposure toan electromagnetic radiation source selected from the group consistingof a broadband flash lamp, a light emitting diode; a laser, and a deepultraviolet (DUV) flash lamp.
 4. The method of claim 3, wherein theelectromagnetic radiation source is the laser, which is selected from adiode laser emitting electromagnetic radiation having a wavelength in arange from 500 nm to 1100 nm, or a carbon dioxide laser emittingelectromagnetic radiation having a wavelength of 9.4 μm or 10.6 μm. 5.The method of claim 4, wherein the laser is a diode laser emittingelectromagnetic radiation having a wavelength in a range from 800 nm to1000 nm.
 6. The method of claim 1, wherein annealing the layer of theblock copolymer comprises: a) selecting a beam shape of theelectromagnetic radiation to distribute power across a predeterminedabsorption area; b) determining a number of scans for the selected beamshape to irradiate a desired area of the layer of the block copolymerwith the electromagnetic radiation; and c) scanning the layer of theblock copolymer with the electromagnetic radiation to heat the layer ofthe block copolymer to the annealing temperature range.
 7. The method ofclaim 6, wherein the scanning the layer of the block copolymer with theelectromagnetic radiation is performed with a single pass.
 8. The methodof claim 6, wherein the scanning the layer of the block copolymer withthe electromagnetic radiation is performed with a repetitive scan or byoffset raster scanning.
 9. A method of patterning a layered substrate,comprising: a) forming a layer of a block copolymer; b) performing afirst annealing treatment of the layer of the block copolymer to affectmicrophase segregation such that self-assembled domains are formed; andc) exposing at least a portion of the layer of the block copolymer toelectromagnetic radiation to heat the exposed portion of the layer ofthe block copolymer to an annealing temperature in a range of 250° C. to500° C.
 10. The method of claim 9, wherein exposing at least a portionof the layer of the block copolymer to electromagnetic radiation isperformed at a power density in a range from 1 W/mm² to 100 W/mm² for aduration of time in a range from 1 second to 10 seconds.
 11. The methodof claim 9, wherein the first annealing treatment comprising a singlewafer bake on a heating plate; a batch wafer bake in a furnace; a singlewafer solvent bake on a heating plate; a batch wafer solvent bake in afurnace; or an absorption based heating method on a single waferprovided by exposure to electromagnetic radiation.
 12. The method ofclaim 11, wherein the first annealing treatment of the layer of theblock copolymer is a single wafer solvent bake on a heating plate or abatch wafer solvent bake in a furnace at a first annealing temperature,which provides the self-assembled domains having a first morphology; andwherein the exposing at least the portion of the layer of the blockcopolymer to electromagnetic radiation is performed to a secondannealing temperature to provide self-assembled domains having a secondmorphology, said first annealing temperature being less than the secondannealing temperature.
 13. The method of claim 9, wherein performing thefirst annealing treatment of the layer of the block copolymer isconducted at a first annealing temperature to provide the self-assembleddomains having a first morphology; and wherein the exposing at least theportion of the layer of the block copolymer to electromagnetic radiationheats the exposed potion of the layer of the block copolymer to a secondannealing temperature to provide self-assembled domains having a secondmorphology, said first annealing temperature being less than the secondannealing temperature.
 14. The method of claim 9, wherein the exposingat least the portion of the layer of the block copolymer toelectromagnetic radiation heats the exposed potion of the layer of theblock copolymer to a temperature sufficient to degrade a first polymerblock of the block copolymer.
 15. The method of claim 14, whereindegrading the first polymer block of the block copolymer increases anetch selectivity of the first polymer block over a second polymer of theblock copolymer.
 16. The method of claim 14, wherein degrading the firstpolymer block of the block copolymer substantially removes the firstpolymer block.
 17. The method of claim 9, wherein exposing at least aportion of the layer of the block copolymer to electromagnetic radiationcomprises: i) selecting a beam shape of the electromagnetic radiation todistribute power across a predetermined absorption area; ii) determininga number of scans for the selected beam shape to irradiate a desiredarea of the layer of the block copolymer with the electromagneticradiation; and iii) scanning the layer of the block copolymer with theelectromagnetic radiation to heat the layer of the block copolymer tothe annealing temperature range.
 18. The method of claim 9, furthercomprising: d) performing a metrology review of the layered substratebetween steps b) and c).
 19. The method of claim 9, wherein the exposingat least a portion of the layer of the block copolymer toelectromagnetic radiation in step c) is performed prior to b), and themethod further comprising: d) performing a metrology review of thelayered substrate between steps b) and c).
 20. The method of claim 18,wherein the metrology review is performed with a reflectometer.
 21. Themethod of claim 18, wherein the metrology review is a pattern defectwafer inspection, and wherein defects are binned.
 22. The method ofclaim 18, wherein the metrology review identifies a number of defectsthat is greater than a threshold value, and wherein step c) is performedover the entire layer of the block copolymer.
 23. The method of claim18, wherein the metrology review identifies a number of defects that isless than a threshold value and identifies a specific defect waferlocation; and wherein step c) is performed on the specific defect waferlocation.